Do I need a better pump.

[77cruiser]

I have this one.

https://www.summitracing.com/parts/crt-m6900/overview/make/chevrolet

But I have 5.5 psi at idle but drops to 3 psi at WOT. That checking at the pump not the carb so it could lower at the carb.
Stock 3/8 line from tank, 1/2 inch pickup in tank no sock to plug.

[qjetsrule]

according to holley's calculator, that pump will supply a 1000hp engine. unless you got a bad pump, something else may be wrong. good luck

http://documents.holley.com/techlibrary_fuel_pump_tech_info.pdf

[Cliff Ruggles]

I tried one of those pumps decades ago and found it to be little if any better than a stock pump.

It would NOT keep up with the 428 engine only making about 400hp that was in my car at that time.  I was trying to feed it with stock lines and modified pick-up as well.  Not sure if it needs bigger lines, or what was going on but I removed the pump and went to an electric pump and things were fine.......Cliff

[77cruiser]

I know the pump should supply more than what I have. I thinking restriction before the pump.

[Jeffs68]

Are you having a drivability issue, is the carb running out of gas, or are you just worried about the pressure drop?

[77cruiser]

I goes lean in 3rd gear.

[Jeffs68]

Are you using a A/F gauge?

Is it losing power?

[77cruiser]

Yes to both.

[Jeffs68]

So what is that 77 cruiser, what motor is in it, what's the carb # (maybe Cliff can make a recommendation) , what rear end and transmission?

[77cruiser]

421 sbc dyned 530 hp, 200-4r 3.73 rear. 4200 lbs. of Monte.

[Jeffs68]

I would try an electric pump.

[77cruiser]

I wish you would have said that.